| Message ID | 20200517012336.382624-1-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | rds: convert get_user_pages() --> pin_user_pages() | expand |
From: John Hubbard <jhubbard@nvidia.com> Date: Sat, 16 May 2020 18:23:36 -0700 > This code was using get_user_pages_fast(), in a "Case 2" scenario > (DMA/RDMA), using the categorization from [1]. That means that it's > time to convert the get_user_pages_fast() + put_page() calls to > pin_user_pages_fast() + unpin_user_pages() calls. > > There is some helpful background in [2]: basically, this is a small > part of fixing a long-standing disconnect between pinning pages, and > file systems' use of those pages. > > [1] Documentation/core-api/pin_user_pages.rst > > [2] "Explicit pinning of user-space pages": > https://lwn.net/Articles/807108/ > > Cc: David S. Miller <davem@davemloft.net> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: netdev@vger.kernel.org > Cc: linux-rdma@vger.kernel.org > Cc: rds-devel@oss.oracle.com > Signed-off-by: John Hubbard <jhubbard@nvidia.com> Applied to net-next, thanks.
diff --git a/net/rds/info.c b/net/rds/info.c index 03f6fd56d237..e1d63563e81c 100644 --- a/net/rds/info.c +++ b/net/rds/info.c @@ -162,7 +162,6 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, struct rds_info_lengths lens; unsigned long nr_pages = 0; unsigned long start; - unsigned long i; rds_info_func func; struct page **pages = NULL; int ret; @@ -193,7 +192,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, ret = -ENOMEM; goto out; } - ret = get_user_pages_fast(start, nr_pages, FOLL_WRITE, pages); + ret = pin_user_pages_fast(start, nr_pages, FOLL_WRITE, pages); if (ret != nr_pages) { if (ret > 0) nr_pages = ret; @@ -235,8 +234,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, ret = -EFAULT; out: - for (i = 0; pages && i < nr_pages; i++) - put_page(pages[i]); + unpin_user_pages(pages, nr_pages); kfree(pages); return ret;
This code was using get_user_pages_fast(), in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages_fast() + put_page() calls to pin_user_pages_fast() + unpin_user_pages() calls. There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Cc: David S. Miller <davem@davemloft.net> Cc: Jakub Kicinski <kuba@kernel.org> Cc: netdev@vger.kernel.org Cc: linux-rdma@vger.kernel.org Cc: rds-devel@oss.oracle.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- net/rds/info.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) base-commit: 3d1c1e5931ce45b3a3f309385bbc00c78e9951c6